1. Field of the Invention
The present invention relates generally to devices for releasably sealing manway openings in tubular fluid conveying systems, and in particular to an apparatus to facilitate releasable sealing of a manway opening in a tubular system for conveying processed food products in liquified form, wherein a swing away assembly permits unsealing of the opening by rotational movement of a manway opening cover about a vertical axis, and limited vertical movement of the cover during such rotational movement.
2. Discussion of the Prior Art
It is known to provide a manway opening in a tubular fluid conveying system. For example, it has long been the practice to provide municipal sewer and water systems with manways, in order to give maintenance personnel access to the interior of such systems. Such manways are traditionally sealed by manway opening covers, which may or may not be integral to such systems by mechanical attachment therewith.
It is also known to provide a manway opening in a commercial tubular fluid conveying system, such as, for example, in food processing operations and the like. Such systems are generally unlike municipal applications in that the former are generally of more reduced scope, and may also be adapted to convey fluids at a variety of pressure levels. For these reasons, commercial fluid conveying systems often include manway openings having releasable covers that are mechanically integrated with the system and capable of forming a tight seal therewith.
Most conventional manway opening covers of the commercial type are attached to the tubular structure by a simple hinge device. In the typical case, the hinge includes a horizontal pivot axis. In this way, most manway covers are opened by lifting the cover in a 180.degree. arc about the pivot axis. Therefore, the manway cover is moved vertically, requiring that there be available sufficient space to accommodate the full diameter of the cover as it is lifted through its arc. In many cases, this requires clearance of more than 24 inches. Obviously, in circumstances where such clearance is not available, the use of a traditional manway opening cover may be prohibited. This presents serious problems where access is necessary and space limited.